/*重置样式*/
*{
	padding: 0px;
	margin: 0px;
}
.box{
	width: 80px;
	height: 80px;
	background: red;
	border-radius: 50px;
	margin-bottom: 20px;
	position: absolute;
}
#btn_move{
	position: absolute;
	top: 100px;
}
#btn_back{
	position: absolute;
	top: 100px;
	left: 100px;
}
